Pivoting tibial tray

ABSTRACT

A tibial component for implantation at a resected tibia. The tibial component includes a medial tray, a lateral tray, and a connection member between the medial tray and the lateral tray. A first fastener extends from the medial tray to the connection member along a first pivot axle to pivotably couple the medial tray to the connection member. A second fastener is spaced apart from the first fastener and extends from the lateral tray to the connection member along a second pivot axle to pivotably couple the lateral tray to the connection member. The medial tray and the lateral tray are configured to pivot independently of one another with respect to the connection member.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/087,479 filed on Apr. 15, 2011, and issued on Nov. 26, 2013 as U.S.Pat. No. 8,591,593, the entire disclosure of which is incorporatedherein by reference.

FIELD

The present disclosure relates to a knee joint prosthesis including atibial tray component having independent and selectively attachablebearings, the tibial tray including a medial tray portion and a lateraltray portion that are independently pivotal around axes that extendgenerally in a medial/lateral direction.

BACKGROUND

This section provides background information related to the presentdisclosure which is not necessarily prior art.

A knee joint prosthesis can generally comprise a femoral component and atibial component. The femoral component and the tibial component can bedesigned to be surgically attached to the distal end of the femur andthe proximal end of the tibia, respectively. The femoral component canfurther be designed to cooperate with the tibial component in simulatingthe articulating motion of an anatomical knee joint. In many examples,the tibial component can further include a bearing component thatincludes articulation surfaces on the medial and lateral side forcooperating with a medial and lateral condyle portion of the femoralcomponent. In some examples, the bearing component can be fixed relativeto the tibial component. In other examples, the bearing component can bea mobile bearing component that has at least a portion that can moverelative to the tibial component during articulation of the femoralcomponent. In some applications, it may be desirable to retain orreconstruct an anterior cruciate ligament (ACL) and/or a posteriorcruciate ligament (PCL).

SUMMARY

This section provides a general summary of the disclosure, and is not acomprehensive disclosure of its full scope or all of its features.

The present teachings provide for a tibial component for implantation ata resected tibia. The tibial component includes a medial tray, a lateraltray, and a connection member between the medial tray and the lateraltray. A first fastener extends from the medial tray to the connectionmember along a first pivot axle to pivotably couple the medial tray tothe connection member. A second fastener is spaced apart from the firstfastener and extends from the lateral tray to the connection memberalong a second pivot axle to pivotably couple the lateral tray to theconnection member. The medial tray and the lateral tray are configuredto pivot independently of one another with respect to the connectionmember.

The present teachings further provide for a tibial component for usewith a resected tibia. The tibial component includes a medial trayportion having a first inferior bone engaging side adapted to engage aportion of the resected tibia and a first superior bearing engagingside. A lateral tray portion has a second inferior bone engaging sideadapted to engage a portion of the resected tibia and a second superiorbearing engaging side. A connection portion is between the medial andthe lateral tray portions. A first pivot axle is removably coupled toeach one of the medial tray portion and the connection portion topivotably couple the first pivot axle to the connection portion. Asecond pivot axle is removably coupled to each one of the lateral trayportion and the connection portion to pivotably couple the second pivotaxle to the connection portion. The first and the second pivot axles areconfigured to move independently of one another.

The present teachings also provide for a tibial component for use with aresected tibia. The tibial component includes a medial tray portionhaving a first inferior bone engaging side adapted to engage a portionof the resected tibia and a first superior bearing engaging side. Alateral tray portion has a second inferior bone engaging side adapted toengage a portion of the resected tibia and a second superior bearingengaging side. A connection portion is disposed between the medial trayportion and the lateral tray portion. A linkage couples the medial trayportion and the lateral tray portion to the connection portion such thatthe medial tray portion and the lateral tray portion are pivotablerelative to each other to position the medial tray portion and thelateral tray portion at different angles with respect to each other. Afirst pivot axle is included with the linkage. The first pivot axle isremovably coupled to each one of the medial tray portion and theconnection portion. A second pivot axle is included with the linkage.The second pivot axle is removably coupled to each one of the lateraltray portion and the connection portion. The first and the second pivotaxles are configured to move independently of one another.

Further areas of applicability will become apparent from the descriptionprovided herein. The description and specific examples in this summaryare intended for purposes of illustration only and are not intended tolimit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure.

FIG. 1 is an anterior perspective view of a knee prosthesis assemblythat incorporates a pivoting tibial tray according to one example of thepresent teachings;

FIG. 2 is an anterior perspective view of the pivoting tibial tray ofFIG. 1;

FIG. 3 is an exploded perspective view of the knee prosthesis assemblyof FIG. 1;

FIG. 4 is a lateral view of the pivoting tibial tray of FIG. 2;

FIG. 5 is a lateral view of the pivoting tibial tray of FIG. 4 and shownwith the lateral tray portion pivoted around a pivot axis that extendsgenerally along a medial/lateral direction in an implanted position; and

FIG. 6 is a lateral view of the pivoting tibial tray shown with alateral bearing and a medial bearing connected to respective lateral andmedial tray portions and shown with the lateral tray portion rotatedgenerally posteriorly in an implanted position about the pivot axis.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference tothe accompanying drawings.

With initial reference to FIGS. 1 and 2, a knee prosthesis assemblyconstructed in accordance to one example of the present teachings isshown and generally identified at reference numeral 10. The kneeprosthesis assembly 10 shown in the drawings is specific for a leftknee. It will be understood, however, that a suitable right kneeprosthesis can be similarly constructed. The knee prosthesis assembly 10can generally include a femoral component 12, a tibial tray 14, a medialbearing 16, and a lateral bearing 18. As will be described, the kneeprosthesis assembly 10 can be used when it is desirable to retain orreconstruct an ACL and/or a PCL.

The respective components of the knee prosthesis assembly 10 can bepatient specific, such that each component can be constructed foroptimal features of a given patient. For example, the bone interfacemargins of the femoral component 12 and tibial tray 14 can be patientspecific for optimized bone coverage. In addition, the overall size,such as anterior-posterior dimensions and bone cut geometry can bedetermined and used for manufacturing the components of the kneeprosthesis assembly 10. Moreover, some articulation features can bedetermined and used as criteria for forming the components of the kneeprosthesis assembly 10. In sum, each of the components of the kneeprosthesis assembly 10 can be patient-specific implant, a semi-customimplant, or an off-the-shelf or standard production implant.

A custom-made implant is a patient-specific, one-of-a-kind implantspecifically made for a particular patient, and consequently, there isno inventory associated with such an implant. Standard or off-the-shelfimplants are available and stocked in a number of sizes, typically sixor more, and a number of configurations or types, including bilateral orunilateral implants, constrained, semi-constrained, mobile, etc. Becauseof the variety of sizes and configurations that are kept in stock to beaccommodated by different patients, a large inventory of standardimplants is created, and several molds for each type and size of implantmay be used. Semi-custom implants can provide an intermediate solutionbetween custom-made and off-the-shelf implants. Semi-custom implantsreduce the size of inventory and molds required for production, whileallowing some degree of patient-specific customization. Additionaldescription of patient-specific implants and semi-custom implants andtheir implementations may be found in co-pending patent application Ser.No. 12/103,824, filed Apr. 16, 2008 and entitled: Method and Apparatusfor Manufacturing an Implant, the disclosure of which is herebyincorporated by reference.

With specific reference now to FIG. 1, the femoral component 12 will nowbe described in greater detail. The femoral component 12 can generallycomprise a cruciate retaining prosthesis and includes various portionsto replace or mimic the distal femur. The femoral component 12 caninclude a medial condyle portion 20 and a lateral condyle portion 22.The condyle portions 20 and 22 can replace the medial and lateralcondyles of a distal femur F. The medial and lateral condyle portions 20and 22 can interconnect and be formed as a single piece with a patellartrack portion 26. The patellar track portion 26 can allow forarticulation of a patella, either natural or prosthetic patella, oncethe femoral component 12 is implanted onto the distal femur. The medialand lateral condyle portions 20 and 22 and the patellar track portion 26can generally define an exterior portion of the femoral component 12.The femoral component 12 can define an opening or passage 30 between themedial and lateral condyle portions 20 and 22. As can be appreciated,the passage 30 can accommodate, and provide clearance for a host ACLand/or PCL or a reconstructed ACL and/or PCL.

The femoral component 12 can include a bone contacting or inferiorsurface 34 adapted to engage the distal femur F. The inferior surface 34can include an anterior surface 36 that can be substantially flat andformed generally parallel to a pair of posterior surfaces 38 a and 38 b.A pair of intermediate surfaces 40 a and 40 b are provided generally atan intermediate portion of the inferior surface 34. A pair of angledanterior transition surfaces 42 a and 42 b generally connect theanterior surface 36 with the intermediate surfaces 40 a and 40 b,respectively. Similarly, a pair of angled posterior transition surfaces44 a and 44 b are provided between the respective posterior surfaces 38a and 38 b and the intermediate surfaces 40 a and 40 b. While notspecifically shown, threaded bosses can be provided on each of theintermediate surfaces 40 a and 40 b, respectively. Similarly, threadedbosses can be provided on the posterior surfaces 38 a and 38 b,respectively. The bosses can be optionally used to threadably couplewith various augments (not specifically shown) as necessary.

The femoral component 12 can be formed as a unitary structure and castof a biocompatible high strength alloy, such ascobalt-chromium-molybdenum alloy or similar suitable material. Allsurfaces, which do not contact the femur F, can be highly polished toprovide smooth articulating bearing surfaces. The interior surface 34 ofthe femoral component 12 can be roughened or uneven or include porousmaterial to allow bone ingrowth or attachment with bone cement. Otherfeatures of the femoral component 12 can include those associated withthe Oxford® Partial Knee marketed by Biomet, Inc.

With reference now to FIGS. 1-3, the tibial tray 14 will now bedescribed in greater detail. The tibial tray 14 can include a generallyU-shaped body 58 having a first or medial tray portion 60, a second orlateral tray portion 62, and a connection portion 64. A slot 66 can beformed in the tibial tray 14 generally between the medial and lateraltray portions 60 and 62. As with the passage 30 of the femoralcomponent, the slot 66 of the tibial tray 14 can accommodate and providea clearance for a host ACL and/or PCL or a reconstructed ACL and/or PCL.During implantation, the tibial tray 14 can be advanced posteriorly,such that the slot 66 can accommodate a host ACL and/or PCL. Ininstances where a reconstructed ACL and/or PCL is used, a tray (andbearing) having a passage can be utilized. One suitable configuration isfurther described in commonly owned U.S. Pat. No. 7,255,715; issued Aug.14, 2007 and is hereby incorporated by reference.

The tibial tray 14 can include an inferior bone engaging side 68 and asuperior bearing engaging side 70. A pair of fins 71 can extend from theinferior bone engaging side 68. While the fins 71 are shown operativelyassociated with the tibial tray 14, other structures suitable forengaging a proximal tibia T can include pegs, posts, or porous materialand can additionally or alternatively be provided on the inferior boneengaging side 68. The medial tray portion 60 of the superior bearingengaging side 70 can include a medial tibial bearing engaging surface72. The medial tibial bearing engaging surface 72 can extend generallyalong a plane 73. The lateral tray portion 62 of the superior engagingside 70 can include a lateral tibial bearing engaging surface 74. Thelateral tibial bearing engaging surface 74 can extend generally along aplane 75. The connection portion 64 can have an upper surface 76 thatextends along a plane 78.

The tibial tray 14 can generally include a locating tab 80 formed on ananterior edge of the medial tray portion 60 and a locating tab 82 formedon an anterior edge of the lateral tray portion 62. A retaining rail 86can be formed around a posterior edge of the medial tray portion 60. Theretaining rail 86 can include a lip 90 and a groove 92. A retaining rail100 can be formed around a posterior edge of the lateral tray portion 62of the tibial tray 14. The retaining rail 100 can generally include alip 102 and a groove 104.

With particular reference now to FIGS. 2 and 3, additional features ofthe tibial tray 14 will now be described. The tibial tray 14 can includea first linkage 120 and a second linkage 122. As will be describedfurther herein, the first linkage 120 and the second linkage 122 canallow a surgeon to selectively and independently pivot the medial trayportion 60 and lateral tray portion 62 relative to each other. In someexamples, the medial tray portion 60 or lateral tray portion 62 can bepivoted relative to the connection portion 64. In this regard, theconnection portion 64 can be aligned in various positions relative toeither the medial tray portion 60 or the lateral tray portion 62.Explained further, the plane 78 of the connection portion 64 can bepositioned coplanar with either, both, or neither of the planes 73 and75. In other configurations, the connection portion 64 can be integrallyformed with one of the medial or lateral tray portions 60, 62 when it isdesirable to provide a tibial tray with only one linkage.

The medial tray portion 60 can rotate around a first or medial pivotaxis 126 defined by a first or medial pivot axle 128 (FIG. 3).Similarly, the lateral tray portion 62 can pivot around a second orlateral pivot axis 130 defined by a second or lateral pivot axle 132.The first linkage 120 further includes a medial bore 134, a headengaging surface 136, and a medial recess 138 provided on the medialtray portion 60. The first linkage 120 further comprises a medial boss140 and a medial receiving bore 142 provided on the connection portion64. In an assembled position (FIG. 1), the medial boss 140 is receivedby the medial recess 138 to provide additional structural support to thefirst linkage 120. It is appreciated that alternate configurations maybe provided. For example, the medial recess 138 may be formed on theconnection portion 64 and the medial boss 140 may be formed on themedial tray portion 60.

The second linkage 122 can further comprise a lateral bore 154, a headengaging surface 156, and a lateral recess 158 provided on the lateraltray portion 62. The second linkage 122 can further include a lateralboss 160 and a lateral receiving bore 162 provided on the connectionportion 64. In an assembled position (FIG. 1), the lateral boss 160 isreceived by the lateral recess 158 to provide structural support to thesecond linkage 122. It is appreciated that alternate configurations maybe provided. For example, the lateral recess 158 may be formed on theconnection portion 64 and the lateral boss 160 may be formed on thelateral tray portion 62.

The medial pivot axle 128 is in the form of a first or medial fastener170 that includes a head 172 and a shaft 174. The head 172 defines atool engaging portion 176. The shaft 174 can define threads 178.Similarly, the lateral pivot axle 132 can generally comprise a second orlateral fastener 180 having a head 182 and a shaft 184. The head 182 candefine a tool engaging portion 186. The shaft 184 can include threads188. As can be appreciated, the medial pivot axis 126 can be providedalong the medial fastener 170. Similarly, the lateral pivot axis 130 canbe provided along the lateral fastener 180. It will also be appreciatedthat while the medial pivot axis 126 and the lateral pivot axis 130 arerepresented in the drawings as coaxial relative to each other, they mayalternatively be parallel and offset relative to each other,intersecting or non-parallel and non-intersecting.

With specific reference now to FIG. 3, the medial and lateral bearings16 and 18 will be described. The medial bearing 16 can generally includea superior surface 202 that substantially conforms to and provides asurface contact with the profile of the medial condyle portion 20 of thefemoral component 12. A channel 204 can be formed along an anteriorinferior surface 206 and that generally tapers anteriorly. A groove 210can be formed around a posterior edge of the bearing 16. The bearing 16can have an inner wall 212 that cooperates with the U-shaped profile ofthe tibial tray 14 to accommodate a host or reconstructed ACL.

The lateral bearing 18 can generally include a superior surface 222 thatsubstantially conforms to and provides a surface contact with theprofile of the lateral condyle portion 22 of the femoral component 12. Achannel 224 can be formed along an anterior inferior surface 226 andthat generally tapers anteriorly. A groove 230 can be formed around aposterior edge of the lateral bearing 18. The lateral bearing 18 canhave an inner wall 332 that cooperates with the U-shaped profile of thetibial tray 14 to accommodate a host or reconstructed ACL.

Connection of the medial bearing 16 to the medial tray portion 60 of thetibial tray 14 will now be discussed. Initially, the inferior surface206 of the medial bearing 16 is located onto the medial tray portion 60of the tibial tray 14. Next, the medial bearing 16 is slidably advancedposteriorly, such that the channel 204 slidably accommodates thelocating tab 80 while the groove 210 locates under the lip 90. Themedial bearing 16 is adapted to be statically secured relative to themedial tray portion 60 of the tibial tray 14 when assembled.

Connection of the lateral bearing 18 to the lateral tray portion 62 ofthe tibial tray 14 is similarly carried out. The medial bearing 16 andthe lateral bearing 18 are both independently formed andinteroperatively selected according to the needs of a given patient. Itis appreciated that other configurations and connection techniques maybe provided for the medial and lateral bearings 16 and 18. Furthermore,while the medial bearing 16 and the lateral bearing 18 are generallyfixed bearing components, a mobile bearing component may be similarlyprovided for either of the medial and/or lateral sides. Furtherdiscussion of such mobile bearing components may be found in commonlyowned and co-pending patent application Ser. No. 12/788,961; filed May27, 2010, entitled Knee Prosthesis; the disclosure of which isincorporated herein by reference.

An exemplary method of rotating the lateral tray portion 62 of thetibial tray 14 relative to a remainder of the tibial tray 14 (i.e., themedial tray portion 60 and the connection portion 64) will now bedescribed. At the outset, the lateral fastener 180 may be located intothe lateral bore 154 such that the head 182 engages the head engagingsurface 156 while the threads 188 are threadably received by the lateralreceiving bore 162. A surgeon can advance a tool into the lateral bore154 to engage the tool engaging portion 186 of the lateral fastener 180.The surgeon can then loosen the lateral fastener 180 such that thelateral tray portion 62 is free to rotate about the lateral pivot axis130 in a first rotational direction (counter-clockwise as viewed in FIG.5). Next, a surgeon can rotate the lateral tray portion 62 about thelateral pivot axis 130 such that the lateral tray portion 62 movestoward a generally anterior sloped position 62 a (phantom line, FIG. 5).Alternatively, the surgeon can rotate the lateral tray portion 62 aboutthe lateral pivot axis 130 in a second rotational direction (clockwiseas viewed in FIG. 5) such that the lateral tray portion 62 moves towarda posterior sloped position 62 b (solid line, FIG. 5) according to theneeds of a particular patient. Once the lateral tray portion 62 has beenrotated about the lateral pivot axis 130 to the desired position, thesurgeon can then tighten the lateral fastener 180 into the lateralreceiving bore 162 until the lateral tray portion 62 is statically fixedrelative to the connection portion 64. It will be appreciated that themedial tray portion 60 may be rotated around the medial pivot axis 126in a similar manner to independently position the medial tray portion 60at a desired slope, if necessary. It is also appreciated that othermechanical configurations may be provided for the medial and secondlinkages 120, 122.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the disclosure. Individual elements or featuresof a particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the disclosure, and all such modificationsare intended to be included within the scope of the disclosure.

What is claimed is:
 1. A tibial component for implantation at a resectedtibia comprising: a medial tray; a lateral tray; a connection memberbetween the medial tray and the lateral tray; a first fastener extendingfrom the medial tray to the connection member along a first pivot axleto pivotably couple the medial tray to the connection member; and asecond fastener spaced apart from the first fastener and extending fromthe lateral tray to the connection member along a second pivot axle topivotably couple the lateral tray to the connection member; wherein themedial tray and the lateral tray are configured to pivot independentlyof one another with respect to the connection member.
 2. The tibialcomponent of claim 1, wherein the medial tray has a first inferior boneengaging side adapted to engage a portion of the resected tibia and afirst superior bearing engagement side; and wherein the lateral tray hasa second inferior bone engaging side adapted to engage a portion of theresected tibia and a second superior bearing engaging side.
 3. Thetibial component of claim 2, wherein the medial tray and the lateraltray are configured to pivot to position the medial tray and the lateraltray at separate angles with respect to each other; wherein both thefirst inferior bone engaging side and the first superior bearingengaging side are concurrently pivotable with the medial tray; andwherein both the second inferior bone engaging side and the secondsuperior bearing engaging side are concurrently pivotable with thelateral tray.
 4. The tibial component of claim 1, wherein the connectionmember, the first fastener, and the second fastener together form alinkage that is movable between a locked position and an unlockedposition, in the locked position one of the medial tray and the lateraltray is fixed relative to the other of the medial tray and the lateraltray, in the unlocked position one of the medial tray and the lateral isconfigured to rotate relative to the other of the medial tray and thelateral tray.
 5. The tibial component of claim 1, wherein the firstfastener is a first threaded fastener and the second fastener is asecond threaded fastener.
 6. The tibial component of claim 1, whereinthe medial tray, the lateral tray, and the connection member form aU-shaped body.
 7. The tibial component of claim 1, wherein the medialtray defines a medial bore that receives a first portion of the firstfastener and the connection member defines a medial receiving bore thatreceives a second portion of the first fastener; and wherein the lateraltray defines a lateral bore that receives a first portion of the secondfastener and the connection member defines a lateral receiving bore thatreceives a second portion of the second fastener.
 8. The tibialcomponent of claim 1, further comprising: a medial bearing thatselectively engages the medial tray; and a lateral bearing thatselectively engages the lateral tray.
 9. A tibial component for use witha resected tibia comprising: a medial tray portion having a firstinferior bone engaging side adapted to engage a portion of the resectedtibia and a first superior bearing engaging side; a lateral tray portionhaving a second inferior bone engaging side adapted to engage a portionof the resected tibia and a second superior bearing engaging side; aconnection portion between the medial and the lateral tray portions; afirst pivot axle removably coupled to each one of the medial trayportion and the connection portion to pivotably couple the first pivotaxle to the connection portion; and a second pivot axle removablycoupled to each one of the lateral tray portion and the connectionportion to pivotably couple the second pivot axle to the connectionportion; wherein the first and the second pivot axles are configured tomove independently of one another.
 10. The tibial component of claim 9,further comprising a linkage including the first pivot axle and thesecond pivot axle, the linkage is configured to couple the medial trayportion to the lateral tray portion such that at least one of the medialtray portion and the lateral tray portion is pivotable relative to theother of the medial tray portion and the lateral tray portion toposition the medial tray portion and the lateral tray portion atseparate angles with respect to each other, wherein (i) both of thefirst inferior bone engaging side and first superior bearing engagingside are concurrently pivotable with the medial tray portion and (ii)both of the second inferior bone engaging side and second superiorbearing engaging side are concurrently pivotable with the lateral trayportion.
 11. The tibial component of claim 10, wherein the linkage ismovable between a locked position wherein one of the medial tray portionand lateral tray portion is fixed relative to the other of the medialtray portion and lateral tray portion, and an unlocked position whereinone of the medial tray portion and lateral tray portion rotates relativeto the other of the medial tray portion and lateral tray portion. 12.The tibial component of claim 9, wherein the first pivot axle includes afirst threaded fastener and the second pivot axle includes a secondthreaded fastener.
 13. The tibial component of claim 9, wherein theconnection portion, the medial tray portion, and the lateral trayportion collectively form a U-shaped body.
 14. The tibial component ofclaim 9, wherein the medial tray portion defines a medial bore thatreceives a first portion of the first pivot axle and the connectionportion defines a medial receiving bore that receives a second portionof the first pivot axle, and wherein the lateral tray portion defines alateral bore that receives a first portion of the second pivot axle andthe connection portion defines a lateral receiving bore that receives asecond portion of the second pivot axle.
 15. The tibial component ofclaim 14, wherein the first pivot axle includes a first threadedfastener that threadably engages the medial receiving bore and thesecond pivot axle includes a second threaded fastener that threadablyengages the lateral receiving bore.
 16. The tibial component of claim 9,further comprising: a medial bearing that selectively engages the medialtray portion; and a lateral bearing that selectively engages the lateraltray portion.
 17. A tibial component for use with a resected tibiacomprising: a medial tray portion having a first inferior bone engagingside adapted to engage a portion of the resected tibia and a firstsuperior bearing engaging side; a lateral tray portion having a secondinferior bone engaging side adapted to engage a portion of the resectedtibia and a second superior bearing engaging side; a connection portiondisposed between the medial tray portion and the lateral tray portion; alinkage that couples the medial tray portion and the lateral trayportion to the connection portion such that the medial tray portion andthe lateral tray portion are pivotable relative to each other toposition the medial tray portion and the lateral tray portion atdifferent angles with respect to each other; a first pivot axle includedwith the linkage, the first pivot axle is removably coupled to each oneof the medial tray portion and the connection portion; and a secondpivot axle included with the linkage, the second pivot axle is removablycoupled to each one of the lateral tray portion and the connectionportion; wherein the first and second pivot axles are configured to moveindependently of one another.
 18. The tibial component of claim 17,wherein (i) both of the first inferior bone engaging side and firstsuperior bearing engaging side are concurrently pivotable with themedial tray portion and (ii) both of the second inferior bone engagingside and second superior bearing engaging side are concurrentlypivotable with the lateral tray portion.
 19. The tibial component ofclaim 17, wherein the linkage moves between a locked position whereinone of the medial tray portion and lateral tray portion is fixedrelative to the other of the medial tray portion and lateral portion,and an unlocked position wherein one of the medial tray portion and thelateral tray portion rotates relative to the other of the medial trayportion and the lateral tray portion.
 20. The tibial component of claim17, wherein the medial tray portion defines a medial bore that receivesa first portion of the first pivot axle and the connection portiondefines a medial receiving bore that receives a second portion of thefirst pivot axle and wherein the lateral tray portion defines a lateralbore that receives a first portion of the second pivot axle and theconnection portion defines a lateral receiving bore that receives asecond portion of the second pivot axle; and wherein the first pivotaxle includes a first threaded fastener that threadably engages themedial receiving bore and the second pivot axle includes a secondthreaded fastener that threadably engages the lateral receiving bore.